Age Matters

Are you too old—or too young—to run your best marathon? To find out, we asked top scientists, coaches, and elite athletes about the impact of aging on endurance. Their answers might pleasantly surprise you.

The two Olympic Marathons held last August in Beijing were literally races for the ages. Kenya's Samuel Wanjiru, 21, broke more than an Olympic record with his 2:06:32 win; he crushed long–held conventional wisdom that marathon performance peaks among runners in their late 20s and early 30s. That conventional wisdom also took a beating when a 38–year–old mother with 10 marathons under her belt, Romania's Constantina Tomescu–Dita, won the women's event.

To a casual observer, these Olympian efforts resembled an emerging trend, with runners young and old bursting through a narrow age boundary. The youth movement included two 25–year–olds–Dathan Ritzenhein and Ryan Hall–who qualified for the U.S. Olympic squad (and finished ninth and 10th, respectively, in Beijing), as well as 19–year–old Kum–Ok Kim, a Korean who finished 12th in the women's race. On the other side of the age spectrum, the U.S. women's team was led by two 35–year–olds–Deena Kastor and Magdalena Lewy Boulet. Meanwhile, "old-timers" and world record holders Paula Radcliffe (34) and Haile Gebrselassie (35) continued posting world–beating performances in races last fall.

Impressive results from youngsters like Wanjiru and older runners like Tomescu-Dita might imply that marathon performance isn't bound by rigid age limits. But are these remarkable performances simply the exceptions to a rule, or are top marathoners truly stretching age boundaries? If so, how, and what are the implications for those of us who finish races far behind? Is there an ideal age to run your best marathon?

We posed these questions to top physiologists, statisticians, coaches, and elite athletes. Their answers paint a picture that offers lots of encouragement to runners of all ages and talents.

First, the bad news. Whether you're an Olympic champ or a midpack runner, your aerobic capacity falls with age. For a healthy, trained athlete, it's not your heart's stroke volume or your ability to extract oxygen from blood that changes with age, says Sandra Hunter, Ph.D., an exercise scientist at Marquette University in Milwaukee. "It's that your max heart rate declines, and no one can change that. It just plummets." While the classic formula for calculating max heart rate (220 minus your age) is just a rough estimate, "The reality is, your max heart rate declines by about a beat a year." No one knows the explanation, but this drop in aerobic capacity explains why the average 50–year–old can't compete against a 20–year–old. "You can't reach the same max heart rate, so you're operating at a lower intensity to begin with," says Hunter.

Aging also leads to a decline in muscle mass, as neurons supplying the muscles begin to die. "If the neurons shrink and die, the muscle fibers die," says Hunter. "Sometimes they get regenerated by new neurons, but as you age you can't keep pace with cell death. Training can slow the process, but it won't end it." The atrophy seems to pick up about age 60, and hits fast–twitch muscle fibers hardest. That's why speed falls off before endurance.

Usually, the age–related change that runners notice first is a drop in their ability to recover from training. Muscles store glycogen, so when you lose muscle mass with age, you also lose some of your glycogen reserves-and this means it takes longer to replenish these stores after a hard effort. Age–related hardening of the arteries also cuts blood flow to your tissues, which means it takes longer for stressed muscle fibers to receive the materials they need to rebuild. In addition, with age your cells and their power–generating components (called mitochondria) begin to accumulate oxidative damage as a by–product of normal metabolism, and as a result they operate less efficiently. Adding insult to injury, levels of testosterone and growth hormones that aid recovery also fall with age, says exercise physiologist Jonathan Dugas, Ph.D., coauthor of the blog Science of Sport.

These physiological changes inevitably alter marathon performance. Though individuals will age differently, studies indicate that beyond about age 35, endurance performance declines by about five to 15 percent per decade, says Dieter Leyk, a researcher at the Institute for Physiology and Anatomy in Cologne, Germany. Leyk recently examined age–related changes in marathon performance among 300,757 runners, and found that among top–10 finishers, running times slowed by about 10.5 percent per decade for men and 14.8 percent among women.

But that study yielded encouraging news for runners outside of the lead pack. For the nonelites tracked, the decline was a little lower-and began later. "For these runners, significant age–related losses in endurance performance did not occur before the age of 50. Mean marathon and half–marathon times were nearly identical for the age groups from 20 to 49 years." The bottom line: Keep up your training, and there's no reason you can't continue to put in solid performances well into middle–age.

In fact, a 2004 study in the British Journal of Sports Medicine found that between 1983 and 1999, New York City Marathon finish times for top runners age 50 and older improved more rapidly than did times for younger athletes. In the same vein, a 2008 Austrian study found no significant difference between the finish times of the top five racers age 35 to 49 in the world mountain-running championships. The authors say the results suggest that VO2max can be held at high levels up to age 49.

"Sure, there's an inevitable decline with aging, but people are breaking down that barrier," says Mark Tarnopolsky, M.D., Ph.D., director of the Neuromuscular and Neurometabolic Clinic at McMaster University in Ontario. Tarnopolsky won an Ontario trail-running series three times in a row, at ages 41, 42, and 43. "Last year, I was running better times in some races than I did in my 20s," says Tarnopolsky, now 45. The difference? He's smarter about training, cross-trains more, and can tolerate pain better than he did when he was younger. Tarnopolsky also says his decades-long endurance base lets him get by on fewer miles.

Whether they're competitive nonelites like Tarnopolsky or world-class performers like Tomescu-Dita, masters runners who perform well past 35 share one trait-they've turned their experience into an advantage. While these runners' physiologies haven't improved with time, they have learned to recognize the types of training their bodies respond to best and they know how to reach their individual peak.

Most studies of physical decline associated with aging haven't factored in the role of physical activity, says Scott Trappe, Ph.D., an exercise physiologist at Ball State University in Muncie, Indiana. "If you look at the cardiovascular system, people lose about one percent per year," says Trappe. "We used to think that decline started at about age 25, but we're starting to see that people can maintain their aerobic capacity longer if they keep training. I'm 42, and my VO2 max is the same as it was in college."

"It's never too late to start," says Tarnopolsky. "We've put adults age 65 and older on exercise programs, and it's incredible the kind of gains they can make." Nonelites who came to the sport late are especially likely to hang on to their performance, or even improve with age. "If you've never trained seriously until age 35, it's quite possible to keep improving in your 40s and beyond," says exercise physiologist Jason Karp, Ph.D., a coach in San Diego. Runners who decide to get serious about the marathon at age 40 can easily continue setting PRs for years because they have so much room for improvement, he says.

As you age, factors like diet, body weight, time constraints, and stress are just as likely to hurt your performance as is age–and those are factors you can actually manage, Karp says. What's more, it's your top–end performance that falls off first, so you're unlikely to see drops in performance like elites who're pushing the limits of human performance. "The higher the level that you've achieved," says Karp, "the farther you have to fall."

From a physiological perspective, there's nothing special about the decade between age 25 and 35, says exercise physiologist Dugas. Instead, he says, the fact that so many marathoners hit their PRs at that age is probably a relic of their career paths, rather than a statement about intrinsic physiology. "There's not any rule that says you peak in your early 30s," says Dugas. "It's just that many runners don't move to the event until later in their careers."

In the absence of injury or mental issues, the world's fastest runner at 10–K should also be the fastest marathon runner, says Dugas. "If we put you on a treadmill and keep upping the pace, the top speed you achieve in that test is what we call peak speed, and it will predict who's the fastest runner for all distance events," he says. As evidence, Dugas points to Ethiopian Haile Gebrselassie, who broke his own world record in the marathon last September in Berlin, having already set records at 5000 and 10,000 meters earlier in his career.

In the past, coaches worried that turning to the marathon too soon would unduly shorten a runner's career. Hudson ran his first marathon at age 12. "I think it hurt my career to go to the marathon so young," says Hudson, who set his PR (2:13) at 23. Today, he doesn't advise kids to begin racing marathons as young as he did, but he says that high school and collegiate runners can handle high volumes of training if they increase their mileage gradually and take steps to avoid burnout.

What successful young marathoners like Wanjiru have in common with older ones like Tomescu–Dita is a solid mileage base. "There are athletes out there running marathons at 21, but if you look at most of them, you'll see they've had a high training volume for a good many years before they've run the event," Mahon says. "Ryan Hall and Dathan Ritzenhein were running 90 miles per week in high school, so for them to make the transition to 100–mile weeks wasn't so hard."

Obviously, young runners outside the elite ranks don't need to attain that kind of mileage. But the same principle applies–to prepare for the marathon, first build a strong endurance base, then adopt a graduated training program that builds to the marathon distance, says Jack Daniels, an exercise physiologist and head distance coach at the Center for High Altitude Training at Northern Arizona University in Flagstaff.

Hall and Ritzenhein are leading a new crop of young runners whose focus on the marathon represents a shift in thinking about the event in this country. "In the United States, the conventional approach has been, spend your young years trying to see how fast you can run on the track, and if you don't make it there, see how fast you can run on the road, and then, if all else fails, try the marathon," says Daniels. He says the collegiate system, with its emphasis on races 10–K and shorter, shuttles young runners away from longer events. "You don't go out and run a marathon in your college years, because it will wipe out an entire season for the school." As a result, says Daniels, "we haven't had many young people get serious about marathons."

But would–be marathoners need not wait to make the jump, argues Salazar. If they build a sufficient base first, there's no reason runners can't try the distance after college, he says.

Hudson agrees. "I think we should push athletes to go to the marathon sooner," he says. "After college is the time to start."

Ritzenhein followed Hudson's advice and made his marathon debut at the 2006 New York City Marathon at the age of 23. That first marathon was a humbling experience. "It went really well for the first 21 miles, then I ran out of fuel," he says. After running with the pack most of the race, he hit the wall in the last few miles and ended up finishing a respectable, but disappointing, 11th place, with a time of 2:14:01. "You can never practice the feeling of hitting the wall," he says. "Until that's actually happened to you, it's hard to have respect for the event. I'm more cautious now. I haven't made those mistakes again, but I still have a lot to learn."

"The marathon has a bigger learning curve than other events," says Daniels. "It might not take more races to feel good at it than for other events, but how often can you do a marathon?"

"It takes time to understand your body and how it responds to the marathon," says Hudson. "In the marathon you go through bad patches just like in life, and you have to be able get through. If you push too early, you'll be in trouble. You have to learn the speed your body can take for that distance."

Marathon training itself requires patience. "Endurance training takes a while to build," says Hudson. "You get a lot stronger over time." Most runners need at least three cycles of marathon training to adjust to the training load. It's not just the mileage–it's dialing in the optimal nutrition, hydration, and recovery. "The marathon is the only event where you're going to run out of sugar, and learning how to train for that is tricky," says Mahon. "Hydration is another huge factor." Once you get those factors tweaked, you need to get some experience racing, and that requires more time still. "To do really well could take in the neighborhood of two to four years," says Mahon.

Exercise physiologist Dugas and his team have studied runners at the Two Oceans ultramarathon in Cape Town, South Africa, and found that people who run the 35–mile race multiple times generally post their best result on the second or third attempt. "I suspect the same thing would happen in the marathon or any distance that is new for a runner," says Dugas. Since his debut, Ritzenhein has run two more marathons, finishing second at the Olympic Trials in 2:11:06, and earning the distinction of top American in the 2008 Olympic Marathon with a ninth–place finish. After three tries, "I think I've figured it out. Now it's just a matter of putting it all together," says Ritzenhein.

If they play their cards right, twentysomethings like Hall and Ritzenhein can look forward to performing at an elite level well into their late 30s, says Salazar. "Ninety percent of elite runners, if they do everything properly, should be running at their best to at least 35," he says. "There's really no reason they can't."

Today's young marathoners have a lot of good times to look forward to, says gold medalist Constantina Tomescu–Dita. "After 30 years, you have more experience, you have more mileage in your legs, and your training is more serious."

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